NATO Secretary-General Jaap de Hoop Scheffer said all 26 member nations will allow their troops in Afghanistan to provide emergency support to allied units anywhere in the country, despite criticism that some are refusing to authorize commanders to send their soldiers into more dangerous regions.
"In case of emergency, every single ally will come to the assistance and help every other ally," de Hoop Scheffer said.
"I'm confident that is the case, because I am confident that all 26 allies have exactly the same interpretation of what solidarity means," he said.
At the NATO summit on Tuesday and Wednesday in Riga, Latvia is expected to focus on the alliance's mission in Afghanistan.
Although all the allies have troops in the 32,800-strong force, Britain, Canada, the US and others in the front line of the battle in the Taliban's southern heartland have complained that Germany, Italy, Spain and France are keeping their troops in the more peaceful north and west.
De Hoop Scheffer appealed for all nations to withdraw "caveats," or restrictions, on where their troops can operate, but he sought to downplay the increasingly bitter debate. He insisted the summit would confirm that under threat, all allies would stand together.
"The Riga summit should underline that in case of emergency every ally will come to the assistance of every other ally," he said during a news conference on Friday.
"That's definitely achievable," he said.
He came to the defense of Germany which has faced criticism for keeping its troops in the northern sector.
"It is unfair and not justified to focus in the question of caveats on Germany," de Hoop Scheffer said.
He emphasized that German troops were "doing a lot."
Germany has 2,700 troops stationed in Afghanistan -- the third largest contingent after the US and Britain.
Although German Chancellor Angela Merkel has insisted they will remain based in the north, the government has said units could be sent for short-term, emergency missions elsewhere in the country.
De Hoop Scheffer said he was confident nations would step up with contributions to the elite NATO Response Force (NRF) in the next few days so that leaders can meet a deadline for declaring the 25,000-strong unit ready for action in Riga.
"We should not miss that deadline," he told reporters.
"We're almost there, but almost is not enough," he said.
He acknowledged it would be a political blow if allies failed to fill remaining gaps in the force, but "not an absolute disaster."
The NRF is the spearhead of NATO's efforts to modernize its military to deal with new threats.
Three years after the divisions over the Iraq war, de Hoop Scheffer stressed the unity of the alliance despite continued US-France splits over a range of issues on the alliance agenda.
He said the summit would produce compromises.
"The allies will find themselves on the different subjects," he said. "I don't see a schism, NATO is in good health."